Soy sauce, which is a traditional Japanese condiment, is produced by the following steps when conducting authentic brewing: inoculating a koji mold into a mixture of heat-denatured protein material such as soybeans and starch material such as wheat and performing culture so as to prepare soy sauce koji, adding the soy sauce koji to an aqueous common salt solution so as to prepare soy sauce moromi (i.e., moromi-mash), fermenting and maturing the soy sauce moromi, and press-filtering the soy sauce moromi. The pH of brewed soy sauce obtained by such an ordinary production method is about 4.8. In addition, since soy sauce has buffering capacity over a wide pH range, if soy sauce is added to a condiment with a pH of less than 4.6, for example, the resulting pH might exceed 4.6.
The pH of a food influences the taste and flavor of the food. It is also strongly associated with the proliferation of microorganisms. In general, if the pH of a food is reduced, proliferation of microorganisms can be suppressed, thereby preventing decay or deterioration of the food. Therefore, it would be useful to reduce pH in order to increase the resistance of a food to microorganisms.
For example, a method that involves adding an acidulant is used to reduce the pH of soy sauce. However, if pH is reduced by this method, an acidic taste and acidic odor are strongly sensed, which in turn results in poor umami in the aftertaste of soy sauce. This is not preferable in terms of flavor. Therefore, if it becomes possible to provide a low-pH soy sauce having reduced acidic taste and acidic odor and good flavor, it would be very useful for achieving microorganism resistance and satisfying taste preferences.
Meanwhile, it is known that soy sauce contains various aromatic components that constitute its rich aroma. These components are combined with each other in a complex manner to result in the unique odor of soy sauce. Ethyl lactate is known as an aromatic component of soy sauce (Non-Patent Document 1). However, it has heretofore been completely unknown that ethyl lactate has effects of intensifying umami, reducing acidic taste and acidic odor, and improving the flavor for a soy sauce with a pH of less than 4.6, which is lower than the pH of conventional soy sauce.